Present-day central Iraq. The Arabs defeat the Sassanids at the Battle of al-Qadisiyyah. The Battle of al-Qadisiyyah[b] (Arabic: مَعْرَكَة ٱلْقَادِسِيَّة) took place between the Rashidun Caliphate and the Sassanid Empire in November 636. It resulted in a decisive victory for the Rashidun army and is considered one of the most significant battles of the Muslim conquest of Persia. After losing al-Qadisiyyah, the Sassanid army was unable to defend itself from the Rashidun siege of Ctesiphon, and was thus forced to retreat from all of Mesopotamia. This development enabled further Rashidun offensives into mainland Persia and culminated in the annexation of the Sassanid Empire in 651.
